VOLUME 38, NO1, FEB-2016
123
 
Comparative Isoconversional Thermal Analysis and Degradation Kinetics of Acetylated Mimosa Pudica (Touch-Me-Not) Hydrogel

Gulzar Muhammad, Muhammad Amin, Muhammad Ajaz Hussain, Muhammad Sher and Mazhar Hussain

Comparative thermal degradation and kinetics of hydrogel of Mimosa pudica (MPH) and acetylated Mimosa pudica hydrogel (AMPH) were investigated. Thermogravimetric (TG) analyses of MPH and AMPH was carried out and analyzed using isoconversional method. Kinetic parameters such as energy of activation (Ea) were calculated by fitting the thermal data to Flynn–Wall–Ozawa (FWO) and Kissinger methods. The order of thermal degradation reactions (n) was evaluated using Kissinger method. TG curves of both MPH and AMPH exhibited two step exothermic degradation. The Ea values calculated by Kissinger and FWO models for first step of degradation of AMPH were found in the range of 105.41-108.49 and 153.67-163.77 kJ mol-1 for the second step which were comparable with the Ea values of the unmodified MPH. The mean values of integral procedural decomposition temperature (IPDT) for MPH and AMPH were found to be 338 °C and 346 °C, respectively. The mean comprehensive index of thermal stability (ITS) was found to be 0.55 for MPH and AMPH showing both materials much stable than many commercially available ingredients used in drug designing.
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Synthesis of Graphene Nano Sheets by the Rapid Reduction of Electrochemically Exfoliated Graphene Oxide Induced by Microwaves

Arshad Hussain Wazir and Imran Waseem Kundi

Graphene has been produced by various methods and techniques from various precursors. Here we demonstrate a simple and fast method of electrochemical exfoliation of graphite to graphene oxide (GO) and then its rapid reduction to graphene nano-sheets (GNs) with the help of microwaves. The samples prepared by this method were characterized with different techniques such as Ultra Violet-Visible spectrophotometry (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Atomic force microscopy (AFM) to confirm their characteristic properties. The UV spectra of GO and GNs showed a sharp and intensive peaks centered at 266.5 nm and 230 nm. The FTIR spectra confirmed the oxidation of graphite and deoxygenation of the GO. Similarly, XRD analysis also confirmed the comparative layer structures of GO and GNS. The typical AFM morphology of GNs drop-casted on glass substrate ascertained the presence of few layers of graphene. This electrochemical exfoliation method and microwaves reduction offers a low-cost and efficient route to produce high quality graphene with high yield.
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Photocurrent Generation through Plant Microbial Fuel Cell by Varying Electrode Materials

Syeda Rubina Gilani, Amara Yaseen, Syed Raza Ali Zaidi, Madiha Zahra and Zaid Mahmood

World is suffering from severe energy crisis and require an efficient renewable energy source.To meet global energy demands, the conservation of renewable energy sources is inevitable. Significant renewable energy can be produced from organic matter that is otherwise considered waste in the form of clean bioelectricity.A less mediator plant microbial fuel cell designed for comparative analysis,power density of two different electrodes; Nickel and Graphite and tested using different local salt marsh grass species Sporobolasarabicus and Cynodondactylon. Both electrodes generated the power density of 23 mW/m2and 10.7 mW/m2respectively withoutusing feed solution.In other experiments using feed solution, the power output was also recorded during the period of two months. The maximum power density recorded as 120 mW/m2 and 58mW/m2respectively from S. arabicus and C. dactylonspecies. Electrodes coupling with same or different electrode materials checked and current voltage relationship with power recorded before and after the application of plant nutrient solution from 1-8th weeks. Maximum current voltage relationship with power measured around 4-6th week for different electrodes and plant species. Graphite proved best electrode material as compared to Nickel for production of electricity.Two conditions existed in the single chamber configuration, one in which cathode was placed inside the soil near roots to consume oxygen and other was to improve power enhancement using plant nutrient solutions. Ohmic resistance and mass transfer losses could be decreased using membrane-lessconfiguration that in fact makes it cost effective because membrane is the primary cost of plant microbial fuel cell. The main reason for not using membraneis that the concentration of oxygen decreases very much in the depth of water or sediment which reduces the need for a membrane. Moreover, the soil or sediment might filter oxygen, acts as PEM and the redox potential of soil also decreases.
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Tensile, Compressive and Thermal Properties of Epoxy / Hollow Glass Beads/ Graphene Ternary Foamed Composites

Xiang-Feng Wu, Yong-Ke Zhao, Ze-Hua Zhao, Yang Sun, Yun Zhang, Sen-Sen Zheng, and Feng Juan Xiao

Hollow glass beads and graphene were used to improve the performances of the epoxy resin. The density, tensile, compressive properties and thermal behaviors of the as-prepared samples were discussed. Experiment results showed that hollow glass beads could effectively reduce the density of the epoxy resin matrix. When the hollow glass beads loading was 30 wt%, the density of the composites was 0.81 g•cm-3. Moreover, graphene could enhance the mechanical performances of the foamed composites. When the graphene loading was 0.75 wt%, the tensile strength, Young’s modulus and strain break of the epoxy/hollow glass beads/graphene ternary samples were 85.2 %, 53.4 % and 11.0 % more than the control binary sample, respectively. Moreover, the compressive strength and modulus were 10.8 % and 68.6 % more than the control binary sample, respectively. In addition, DSC and TG results showed that graphene could accelerate the curing and improve the thermal stability of the foamed composites.
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Synthesis and Some Physical Features of Silica Xerogels Derived by Sol-Gel Method

Syed Rashid Saeed, Syed Sakhawat Shah, Muhammad Waseem, Wajid Rehman and Muhammad Siddique

This paper is concerned about the synthesis of silica xerogel samples at different values of pH by using inexpensive silica precursor (Na2SiO3). The synthesized xerogels were tested for physical tests like Scanning Electron Microscopy (SEM), X-rays diffractions (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy. The micrographs of the gel obtained at higher pH values of the precursor solution showed that the particles are glassy and shiny in appearance. In the X-rays diffractogram of the gel sample where 6 % sodium silicate was used displayed only a single peak at 2 = 74o which points towards the crystalline nature of the sample. However, the xerogel with 4 % of the silica precursor showed no peak except a broad peak centered at 2θ angle of 22° which confirmed its amorphous nature. The crystallinity was observed to be affected with the change in pH of the precursor during the gel fabrication.
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MILK: Carrier of Heavy Metals from Crops through Ruminant Body to Human Beings

Fozia Batool, Shahid Iqbal, Muhammad Ilyas Tariq, Jamshed Akbar, Sobia Noreen, Muhammad Danish and Kim Wei Chan

Exposure of heavy metals to humans is higher today than ever before in modern history due to continuously increasing industrialization around the globe. Industrial wastes are rich in heavy metals and these wastes are discharged near agricultural fields or mixed with soil, from where these metals are taken up by the crops and are finally transported to humans. Due to this increasing threat of heavy metals contamination in food, it is necessary to analyze the food before consumption. Content of selected metals (Cd, Cr, Cu, Pb and Zn) in cow milk is determined in this study. To investigate the possible pathways of these metals to reach in milk; fodder supplied to these cows was analyzed besides analysis of soil samples on which this fodder was grown. Pearson correlation among metal contents in soil-forage and forage-milk was also determined to check the route of transfer of these metals from soil to forage and from forage to milk. It was found that a strong correlation (p < 0.5) exists for Cr, Cd, Cu and Zn. This shows that these metals are mainly transferred through soil. However, a weak correlation was found for Pb, which shows that Pb is introduced into forage through some other source (automobile exhaust etc.). A comparison of present study is also done with previously reported work from other countries on metal contents in milk and findings of both the studies were in good agreement mutually.
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Corrosion Resistance Synergistic Performance of Alkyd Based Triplex Coating System Impregnated with Fe, Zn, Cr and Ti based Corrosion Inhibitors

Humaira Bano, Azhar Mahmood and Syed Arif Kazmi

An alkyd polymer based triplex coating system embedded with Iron Oxide, Zinc Chromate and Titanium Dioxide inhibitors was studied to ascertain its corrosion resistance synergistic performance at various anthropogenic and metropolitan sites of Karachi coastal city while accelerated salt spray test was also carried out for reference. Coating performance was ascertained by visual morphological inspection, gloss measurements, Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray (EDX) analysis and by Fourier Transform Infrared (FTIR) Spectroscopy. EDX results substantiated a general increment in oxygen/carbon ratio and revealed that chromium was conspicuously vanished in all exposed coating systems. Diminution trend in gloss value, ex-corporation of inhibitors on the coating surface plus depletion of morphological features witnessed through SEM micrographs and curtailment of ester linkage signals in FTIR spectrum, concluded that an insignificant protection offered by the alkyd triplex coating due to its permeability upon weathering which led to ex-capsulation of inhibitors under moist conditions. Appraisal of these results have furnished an average coating performance correlation of 704 hpy (hours of salt spray test equivalence per year exposure test) at marine test site and 614 hpy at industrial test site in terms of blistering while equivalence mean in terms of rusting were found 815 hpy and 622 hpy at marine and industrial test sites respectively.
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Effects of Nickel Oxide Nanoparticles on Visual Processes and Electro-Retinography Waves in the Bullfrog Eye

Fazli Wahid, Romana Khan, Taous Khan, Mazhar Ul-Islam and You Young Kim

The nickel oxide nanoparticles were synthesized and their effects were evaluated on the visual system of the vertebrate eye. The physico-chemical characterization of the prepared nanoparticles was carried out through transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements. Electroretinography (ERG) was used to evaluate the possible effects of the nickel oxide nanoparticles on the visual system. TEM and XRD measurements demonstrated that the size of nickel oxide nanoparticles was in the range of 4-10 nm. ERG results showed that nickel oxide nanoparticles markedly improve ERG b-wave amplitude during dark-adapted and in the presence of background light. Nickel oxide nanoparticles increased visual sensitivity by 0.4 log units of light intensity and also shortened the time required for rhodopsin regeneration. In conclusion, nickel oxide nanoparticles have positive effects on visual processes in vertebrate eye.
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Development of a Validated Colorimetric Assay Method for Estimation of Amikacin Sulphate in Bulk and Injectable Dosage Form

Naureen Shehzadi, Khalid Hussain, Muhammad Tanveer Khan, Muhammad Salman, Muhammad Islam and Humaira Majeed Khan

Amikacin sulphate is devoid of any chromophore and/or conjugated system prerequisite for UV and florescent light detection (FLD). Hence, there is a need of simple and reliable methods for introducing chromophore in the structure of amikacin sulphate for its determination using UV and FLD. Therefore, the present study describes the development and validation of a simple, economical and fast colorimetric method for estimation of the drug. The analyte and aqueous ninhydrin solution upon heating for 2-5 min produced the Ruhemann purple colored drug-derivative which was detected at two wavelengths, 400 nm and 567 nm. Beer’s law was obeyed over the concentration ranges from 0.417 mg/ml to 2.500 mg/ml. The method was found to be reliable (95.07 – 100.52 % recovery at 400 nm and 96.04 – 99.89 % at 567 nm), repeatable - intraday accuracy - (95.07 – 100.52 % at 400 nm and 96.04 – 99.84 % at 567 nm) and reproducible -inter day accuracy - (95.25– 99.91 % at 400 nm 96.52 – 99.89 % at 567 nm) with relative standard deviation less than 5 %. The results of the present study indicate that the method is easy to perform, specific and sensitive, and suitable to be used for the determination of amikacin sulphate in bulk and injectable dosage forms using less expensive/laborious derivatization.
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Synthesis, Characterization, Antimicrobial and Antileishmanial Activities of Amide derivatives of L-tartaric acid

Sher Wali Khan, Javid H. Zaidi, Nahed Nasser E. El-Sayed, Khalid Mohammed Khan, Sammer Yousuf, Momin Khan, Akhtar Nadhman, M. Naveed Umar, Shahnaz Perveen and Ghulam Abbas Miana

Sixteen (16) chiral, amides were synthesized from commercially available L-tartaric acid, having two asymmetric centers and C2 axis of symmetry. The diacid functionality of L-tartaric acid was protected as dimethyl ester and dihydroxy groups as acetonoid. The partial hydrolysis of acetonoid of dimethyl ester gave the corresponding monoester. Monoester upon treatment with different substituted aromatic amines gave desired amides (1-8). Amides (1-8) afforded deprotected compounds (9-16) after reacting with acetyl chloride and methanol. All the compounds were characterized by using spectroscopic techniques such as IR, 1H-NMR, 13C-NMR, and EIMS. The compounds gave reasonable elemental analyses. The structure of compound 6 was unambiguously obtained by X-ray crystallography. Protected (1-8) and deprotected amides (9-16) were tested for their antileishmanial (against Leshmania tropica KWH23 Promastigotes) and antimicrobial activities at different concentrations against different strains of bacteria and fungi.
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